I've made my own invincible units mod, as an actual mod to be placed in the mod folder. It's identical to the downloadable one, except that the damage translation modifier is 0 rather than -1 (I don't want units to heal when taking damage either).

My infantry is utterly invulnerable, but vehicles are still fragile as hell. My tanks blow up from one direct hit by Panzers, and even my heavy tanks keep getting detracked or have their turret destroyed.